In general, a small-sized camera module is mounted in a mobile terminal such as a smartphone. In such a camera module, a lens driving device (for example, PTL 1) is employed. The lens driving device has an auto-focusing function of automatically performing focusing for capturing a subject (hereinafter referred to as “AF (Auto Focus) function”), and a shake-correcting function (hereinafter referred to as “OIS (Optical Image Stabilization) function”) of correcting shake (vibration) upon capturing an image to reduce the irregularities of the image.
The auto-focusing and shake-correcting lens driving device includes an auto-focusing driving part (hereinafter referred to as “AF driving part”) for moving the lens part in the light axis direction, and a shake-correcting driving part (hereinafter referred to as “OIS driving part”) for swaying the lens part in a plane orthogonal to the light axis direction.
The AF driving part includes, for example, an auto-focusing coil part (hereinafter referred to as “AF coil part”) disposed around the lens part, and an auto-focusing magnet part (hereinafter referred to as “AF magnet part”) disposed separately from the AF coil part in the radial direction. Automatic focusing is performed by moving an AF movable part including the lens part and the AF coil part with respect to an AF fixing part including the AF magnet part in the light axis direction with use of a driving force of a voice coil motor composed of the AF coil part and the AF magnet part, for example.
Here, a lens position for bringing a subject at a smallest capture distance (a position on the most light reception side) into focus is called “macro position,” and a lens position for bringing a subject at the infinity (a position on the most imaging side) into focus is called “infinity position.” That is, the range from the macro position to the infinity position is the movable range of the AF movable part.
The OIS driving part includes a shake-correcting magnet part (hereinafter referred to as “OIS magnet part”) disposed at the AF driving part, and a shake-correcting coil part (hereinafter referred to as “OIS coil part”) disposed separately from the OIS magnet part in the light axis direction, for example. A shake correction movable part (hereinafter referred to as “OIS movable part”) including the AF driving part and the OIS magnet part is supported by a supporting member so as to be separated from a shake-correcting fixing part (hereinafter referred to as “OIS fixing part”) including the OIS coil part in the light axis direction. The OIS movable part is swayed in a plane orthogonal to the light axis direction by use of a driving force of a voice coil motor composed of the OIS magnet part and the OIS coil part, and thus shake correction is performed (so-called barrel shift system). The OIS magnet part can also serve as the AF magnet part, and with such a configuration, the size and the height of the lens driving device can be reduced.
The lens part is attached to the lens driving device including the AF driving part or the OIS driving part, and these parts are housed in a cover, thereby assembling a camera module. In addition, preferably, the cover is composed of a conductive material, and grounded in view of preventing generation of noise (so-called shield cover). For example, in the case where a lower inner peripheral surface of the cover is brought into contact with and bonded to a side surface of a peripheral portion of the base member serving as a part of the OIS fixing part, the cover and the ground terminal can be electrically connected with each other by disposing the ground terminal along the side surface of the peripheral portion of the base member.
In the case where the cover is grounded with the above-described structure, the base member and the cover are attached to each other, and thereafter an adhesive agent is supplied to the contact surface between the base member and the cover. In the case where the attachment position of the ground terminal is shifted with an attaching tolerance, the adhesive agent advances to the contact surface between the cover and the ground terminal in some situation. In this case, the cover and the ground terminal are partially insulated, and consequently conduction failure may possibly occur with impact of dropping or the like.